72 lines
1.5 KiB
JavaScript
72 lines
1.5 KiB
JavaScript
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/**
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* Accepts any node Stream instance and hijacks its "write()" function,
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* so that it can count any newlines that get written to the output.
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*
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* When a '\n' byte is encountered, then a "newline" event will be emitted
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* on the stream, with no arguments. It is up to the listeners to determine
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* any necessary deltas required for their use-case.
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*
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* Ex:
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*
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* var cursor = ansi(process.stdout)
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* , ln = 0
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* process.stdout.on('newline', function () {
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* ln++
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* })
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*/
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/**
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* Module dependencies.
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*/
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var assert = require('assert')
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var NEWLINE = '\n'.charCodeAt(0)
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function emitNewlineEvents (stream) {
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if (stream._emittingNewlines) {
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// already emitting newline events
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return
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}
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var write = stream.write
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stream.write = function (data) {
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// first write the data
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var rtn = write.apply(stream, arguments)
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if (stream.listeners('newline').length > 0) {
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var len = data.length
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, i = 0
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// now try to calculate any deltas
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if (typeof data == 'string') {
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for (; i<len; i++) {
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processByte(stream, data.charCodeAt(i))
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}
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} else {
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// buffer
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for (; i<len; i++) {
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processByte(stream, data[i])
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}
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}
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}
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return rtn
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}
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stream._emittingNewlines = true
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}
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module.exports = emitNewlineEvents
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/**
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* Processes an individual byte being written to a stream
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*/
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function processByte (stream, b) {
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assert.equal(typeof b, 'number')
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if (b === NEWLINE) {
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stream.emit('newline')
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}
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}
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